prepares for a gradual drawdown from afghanistan. >>> when we come back here tonight, new research on head injuries and dementia and alzheimer's and a group that the researchers are most concerned about tonight. >>>, and later, they may have come up short in the end, but the u.s. women's world cup team members are still american idols. >>> we're back, as promised, with news that may help solve a mystery. researchers set out to see what happened later in life to those americans who served in vietnam. what they found, presented today at the annual meeting of the alzheimer's association, is that head injuries during that war may be linked to dementia years later. and the findings could mean a frightening scenario, of course, for veterans of our current dual wars. thousands of them have come home suffering brain injuries. our report tonight from our chief science correspondent robert bazell. >> reporter: richard wanamaker, 62 years old, is suffering twice because of his military service. an initial traumatic brain injury or tbi. now, decades later, increasing memory loss. today's study lo